text: RNA polymerase  is composed of a core and a holoenzyme structure. The core enzymes contains the catalytic properties of RNA polymerase and is made up of ββ′α2ω subunits. This sequence is conserved across all bacterial species. The holoenzyme is composed of a specific component known as the sigma factor (σ-factor). The sigma factor functions in aiding in promoter recognition, correct placement of RNA polymerase, and beginning unwinding at the start site. After the sigma factor performs its required function, it dissociates, while the catalytic portion remains on the DNA and continues transcription. Additionally, RNA polymerase contains a core Mg+ ion that assists the enzyme with its catalytic properties. RNA polymerase works by catalyzing the nucleophilic attack of 3’ OH of RNA to the alpha phosphate of a complementary NTP molecule to create a growing strand of RNA from the template strand of DNA. Furthermore, RNA polymerase also displays exonuclease activities, meaning that if improper base pairing is detected, it can cut out the incorrect bases and replace them with the proper, correct one.